Gels are structures containing a fluid, such as an organic solvent or water, within a three-dimensional network structure formed by a substance (gelator) that is capable of forming gels. A gel is referred to as an organogel when the fluid is an organic solvent and is referred to as a hydrogel when the fluid is water. Organogels have been used for adjusting the fluidity of cosmetics or coating materials in the fields of cosmetics, pharmaceuticals, agricultural chemicals, food products, adhesives, coating materials, resins, and the like. In addition, organogels have been widely used in the field of environmental conservation, for example, through the formation of solid matter by gelating the waste oil so as to prevent the water pollution or the like.
Studies on the gelators have been carried out mainly on the polymeric compounds. However, in recent years, research and development of low molecular compounds to which introduction of various functions is relatively easy compared to the polymeric compounds have been conducted. As mentioned above, organogels have been used in a wide range of fields, and further expansion in the fields of application therefor has also been expected in the future. For this reason, in the expansion of fields of application for the organogels, a low molecular weight compound serving as a gelator (hereafter, sometimes referred to as a low molecular weight gelator) is required to have a capacity to form gels in a wide variety of organic solvents. With respect to such challenges, a urea compound has been disclosed in the past, which is a low molecular weight gelator capable of forming highly stable gels when added in various organic solvents in small quantities (for example, refer to Patent Literatures 1 and 2).
Conventional low molecular weight gelators include a long chain alkyl group as in the urea compound described in Patent Literatures 1 and 2. In addition, the gelators have a structure with low symmetry. For this reason, it has not been easy to synthesize the derivatives thereof, and the functions of low molecular weight gelators have been difficult to predict. On the other hand, a highly symmetric urea compound having a benzene ring as a parent ring and includes no long chain alkyl group has been developed (for example, refer to Patent Literature 3). Since the urea compound described in Patent Document 3 is highly symmetric, a theoretical molecular design becomes possible.